Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!eecae!netnews.upenn.edu!eniac.seas.upenn.edu!depolo
From: depolo@eniac.seas.upenn.edu (Jeff DePolo)
Newsgroups: sci.electronics
Subject: Re: Radar detection
Message-ID: <7540@netnews.upenn.edu>
Date: 1 Feb 89 03:13:57 GMT
References: <311@serene.UUCP> <1400@ucsd.EDU> <6742@fluke.COM> <14011@cup.portal.com> <14101@cup.portal.com>
Sender: news@netnews.upenn.edu
Reply-To: depolo@eniac.seas.upenn.edu.UUCP (Jeff DePolo)
Organization: University of Pennsylvania
Lines: 46

In article <14101@cup.portal.com> A-N-Onymouse@cup.portal.com (John - DeBert) writes:
>Just heard a news story on KUSW that said that some police departments were 
>testing laser speedd "radars." No details were provided about how they work
>but it did say that the laser had to be aimed very carefully to work
>correctly.
>
>Also mentioned, laser detectors for cars to detect the speed traps.
>
>A-N-Onymouse@cup.portal.com

There is a laser speed measuring device currently being tested.  It's
made by a company in Littleton, Colorado (don't remember the name).

According to the specifications, the beam width is only 6' at 250 feet,
making it VERY hard to detect.  Since it will be switched on only when a
car is within range, detection is almost impossible.  Add to that the
coherent effects of a laser beam and you're chance of picking up even 
some of the reflected signal are next to nil.

The unit is supposed to seel for about $3,500.  This is more than twice
as much as the best radar unit on the market today which is only $1,500.
One of the most popular radar units these days (a favorite of my home
state, Colorado, and of many others) sells for UNDER $400.  I don't see
much of a market for the laser-radar units.  However, with such a narrow
beam width, they would be very effective in high-volume situations where
normal radar is useless because of is wide beam width.  Most normal radar
units range anywhere from a beam width of 12 degrees to 25 degrees.  By
the way, the beam width is measured from the half-power points off the
center of the axis of the beam.  So the beam is actually wider than 15
degrees (or whatever the horn on the antenna is rated at).  This makes
radar useless when there is more than 1 car in or near the beam.  I guess
the laser radar would be nice in that respect, but it probably won't make
the state any richer since any officer can fill his ticketbook given just
a normal radar unit and any decent stretch of highway.  $3,500 dollars
of your tax dollars may go toward buying a laser radar unit, just for the
purpose of taking even more money from you in the form of speeding tickets.
Ain't America great?

						--- Jeff
+----------------------------------------------+------------------------------+
|  Jeff DePolo  [depolo@eniac.seas.upenn.edu]  | o  The best things in life   |
|   =>  The University of Pennsylvania  <=     |    come in six-packs.        |
| Class of 1991 - Computer Science Engineering | o  Life begins at 85 MPH.    |
+----------------------------------------------+ o  It's not illegal if they  |
| DISCLAIMER:  Someone else used my account.   |    don't catch you.          |
+----------------------------------------------+------------------------------+